Wow! The NUCLEO-F401RE is really fast with just polled SPI. I am using a stock Adafruit data logging shield. I now have a new, not SdFat, file system library running well enough to do a first benchmark. This is with a simple polled SPI library, not DMA. Here is the first result, no attempt to optimize: NUCLEO-F401RE STMicroelectronics Datasheet. Download NUCLEO-F401RE Datasheet. Datasheet Snippet: The Arduino™ Uno V3 connectivity support and the ST morpho headers allow the easy expansion of the functionality of the STM32 Nucleo open development platform with a wide choice of specialized shields.
Some NUCLEO_F401RE boards come in different hardware revisions, which is located on a sticker at the backside of the board. The revision C-01 has a different configuration for the high speed external clock (HSE). This could be fixed by reconfiguring some solder bridges as mentioned in the user ... 2N3904 Transistor and Specifications. 2N3904 Datasheet. 2N3904 Circuits. The 2N3904 is common general-purpose low-power NPN transistor used amplifying or switching applications. It is typically used for low-current, medium voltage, and moderate speed purposes.